1. Field of the Invention
The present invention generally relates to communication systems and methods and more particularly to communication systems based on ultrasonic signals and methods for short-range communication using ultrasonic signals.
2. Description of the Related Art
Radio Frequency (RF) transmission is used by wireless communication technologies at different frequencies for carrying information by means of modulating an RF signal with the information to be transmitted. Typical frequencies used in wireless communication are in the range of 0.1 GHz-10 GHz, but some applications may extend below or above this range. Techniques for carrying the information over an RF signal include various digital modulation schemes, as well as analog modulation schemes.
Independently of the RF frequency used and the modulation scheme employed, all these technologies and appliances inherently rely on electromagnetic radiation for their operation and wireless communication functions. Therefore, essentially all consumer devices that contain wireless communication functionality emit electromagnetic radiation.
In recent years there is a growing awareness to health hazards related to exposure to radiation emitted from commonly used devices such as cellular phones, cellular modems and other wireless devices. Since there has been an enormous increase in usage of these devices more and more studies are being conducted some yielding quite alarming results and conclusions.
The relation between health related hazards and electromagnetic radiation is and continues to be the subject of extensive research and scientific/medical expert concern. Many studies carried out over the recent years show direct and/or indirect relation between health risks and exposure to electromagnetic radiation emitted by wireless devices such as mobile phones. Most studies show that health risk increases in proportion to factors such as radiation level and exposure duration.
Many appliances related to mobile devices that connect to the mobile device and allow outputting and inputting voice and other related data therefrom such as wireless headsets for mobile phones, do not reduce radiation exposure and/or emission and in some cases even increase health risk by directing more of the emitted radiation towards the user's head.
An Israeli company called “Intelligo” has published a product (see: http://www.globes.co.il/news/article.aspx?did=1000640560) that enables using ultrasonic communication for transmitting data from cellular phones to specially designed end devices using a designated application uploaded on the cellular phone. This communication link is specifically designed for transmitting data from a mobile phone application to a designated children electronic toy using ultrasonic communication. This company does not allow reducing exposure to electromagnetic radiation while using the cellular phone as a long-distance communication device for conducting phone-calls and-or for sending/receiving text messages and the like.